I read a science fiction story several years ago, in which humanity is late to space travel, because we missed an obvious step around 1500 AD or so. We are then visited by aliens who try to conquer us with muskets and crossbows.

Perhaps is is even more extreme, the aliens make their spacecraft out of rope and planks. Because this is tricky (you try it), they are also really good at making these crop circles.

This would also explain why said aliens don't take over the planet - their technology is too far behind ours.

i hate to be picky.... BUT...the makers have got the perspective slightly wrong on this one, the taper on the shape is too great for it to fit snugly inside a cube, as i suspect it is supposed to. if you converge the vertical lines then the shape it would fit inside is conical. it's quite subtle, but to me it just doesn't sit right. it could be the photo i suppose or maybe it's back to the drawing board...

this cube makes a 4 sided tetrahedron pyramid. build one of these cubes out of cardboard and then make 30 more and find out for yourself that they stack into a tetrahedron pyramid. a platonic solid. the box in the middle when looking at it from a real 3-D cube WILL turn into a hologram. and when you build a pyramid out of these cubes and take off the top cube and look into the pyramid there is this "room" with the hologram inside this room... such as to mimic the eye of the illuminati pyramid.
the cube sits on one of its 8 punched out corners and in theory if you can get a house or a tv to sit on its corner in theory you will be able to build a 4 sided tetrahedron pyramid... there is so much to say about this one crop circle of all the circles this one circle is viable and able to be used. wish I could post a pic of what im talking about you will have to see them on my fb page at joe blechl. I hope you are as amazed as I was.